It's not just FSD footage. Footage was recorded while the cars were charging. From Reuters:

As an example, this person recalled seeing “embarrassing objects,” such as “certain pieces of laundry, certain sexual wellness items … and just private scenes of life that we really were privy to because the car was charging.”

To be clear, looking at video surreptitiously recorded inside peoples' homes is absolutely spying. And saying you get actual consent from click-through "opt-in" forms which opting out would kill huge swaths of their car's functionality, and not deliberately and loudly informing them of how invasive the videos were is frankly, ridiculous. Those forms are obviously pretext for tech companies to do things with people's data that they'd never consent to if they really understood the implications.